This invention relates to a method of reinforcing structures and has particular but not exclusive application to reinforcing offshore structures such as oil and gas rigs.
It is often required to increase the load that existing structures such as oil rigs can carry. Typically such structures are constructed from large steel tubes.
One way of reinforcing the structure is by welding on new structures or additional members. However, for a structure that is already close to its loading limit there is a fundamental difficulty that only the additional load that is subsequently applied can be shared by the new structure; the existing load will be carried entirely by the existing structure. One way to avoid this difficulty is to remove all or part of the load when carrying out the retrofit. Upon re-loading, the new structure will take a greater share of the overall load than it would if the load could not be removed. Normally, for large structures, there is limited scope for removing load, so that optimum load sharing is not achievable. Consequently, the scope for carrying additional load may be very limited.
In addition, in the case of oil and gas rigs that are required to remain operational throughout any retrofits, welding or other operations involving the use of naked flames, are not allowable.